1. Field of the Invention
The present invention generally relates to an electrical connector, and more particularly to a socket connector having a plurality of contact terminals, each of the contact terminals includes a pair of contact arms both adapted for reliably ensuring electrical connection between a circuit board and a corresponding conductive pad of a processor.
2. Description of Related Art
As the rapid development of electronic technology, the speeds of computers are becoming faster and faster for complying with the public's requests on processing and transfer of huge amount of data, such as image data or three dimensional data. A heart of a computer is a computer processor. The processor is always in a constant state of technical innovation. As the speed of the processor increases, it becomes increasingly important for all the components in the data processing path to become faster in order to prevent data congestion or “bottlenecks.” This includes the interface that connects a processor to a printed circuit board (sometimes referred to as a “mother board”).
One example of such an interface is referred to as a Pin Grid Array (PGA) socket. The PGA socket is designed to receive a pin grid array of a processor and to establish an electrical connection between the processor and the printed circuit board. The PGA socket varies in types in accordance with such design factors as the number of pins in the pin grid array, the type of contacts located in the PGA sockets, the locking mechanism for maintaining a connection between the contacts and the pins of the pin grid array, and so forth.
Both of U.S. Pat. No. 5,722,848 issued to Lai on Mar. 3, 1998 and U.S. Pat. No. 6,371,784 issue to Scholz on Apr. 16, 2002 disclose a Zero Insertion Force (ZIF) PGA socket. A ZIF PGA socket is a PGA socket that requires little or no force to insert the pins of the pin grid array into the corresponding PGA sockets used for receiving a PGA processor. Refer to FIG. 5, A ZIF PGA socket 10 includes a base 20 having a plurality of passageways 22 extending vertically therethrough for receiving a corresponding number of contacts 24 therein, and a cover 26 having a corresponding number of holes 28 extending therethrough in alignment with the corresponding passageways 22 in the base 20 for allowing a corresponding number of pins extending from the PGA component. A lever 44 includes a cam shaft 48 embedded within a channel 50 formed adjacent the rear region of the socket 10 wherein cover 26 includes a retention device 54 and the base includes a restriction plane 64 to cooperate with the retention device 54 of the cover 26, and both of the retention device 54 and the restriction plane 64 are disposed adjacent the cam shaft 48 for efficiently fastening the cover 26 and the base 20 together to resist the larger resistance force occurring thereabout during the socket 10 in a closed state.
The base 20 showed in FIG. 6˜9 includes a plurality of passageways 22 in which a plurality of corresponding contacts 24 are contained. The bottom of contact 24 has a solder recess for receiving a solder ball 208 adapted for mating on a circuit board in subsequent soldering process. When the lever 44 is located in a vertical position, the cover is located at the first position, in which a hole in the cover is completely in align with a corresponding passageway 22 in the base 20. In this position, a pin leg 210 of a CPU can be inserted from the cover 26 into the passageway 22 without any engagement with the contact 24 (Position B in FIG. 9). When the CPU is properly seated on the cover 26, then the lever 44 is moved from the vertical position to a horizontal position, and simultaneously driving the cover 26 from the first position to the second position. After that, the pin leg 210 of the CPU is then in contact with the contact within the base (Position A in FIG. 9).
This PGA base and cover arrangement, however, requires use of a mechanism, such as a lever assembly, thereby introducing excess parts and manufacturing cost. The PGA base and cover arrangement also requires additional space for the contacts as the arms on the contacts must flex outward away from each other to receive the processor pins. These drawbacks are especially troublesome in applications where space is at a premium, such as on motherboards for desktop and laptop computers.
Consequently, Both of U.S. Pat. No. 7,001,197 issued to Shirai on Feb. 21, 2006 and U.S. Pat. No. 6,887,114 issue to Liao on May 3, 2005 disclose another type of socket named as land grid array (LGA) socket which is mounted onto the motherboard by compression-type of contact, or LGA type contact, requiring only vertical compression to allow a processor and a circuit board to electrically communicate. Refer to FIG. 10 and FIG. 11, the LGA socket 300 generally includes a metal stiffener 302 with an insulative housing 304 securely supported therein. It should be recognized that the insulative housing 304 comprising an interior area having a plurality of apertures 312 arranged in a manner of an array in which corresponding contact terminals 314 are constrained. Then a metal clip 306 is pivotally assembled to the stiffener 302. On the other hand, the clip 306 is pivotally assembled to the other side of the stiffener 302 and when the clip 306 is closed to the stiffener 302, a lever 308 having a cam 310 can lock the clip 306 to a closed position. By this arrangement, if before the clip is closed, and a CPU is seated on the housing, then the clip 306 will tightly press the CPU toward the housing 304 ensuring proper electrical connection therebetween.
FIG. 12 discloses a detailed structure of a metal contact 314 for the LGA socket 300. The metal contact 314 is mainly made of a rectangular support body 316, a base portion 318, a contact beam 320 and a solder ball pad 322. The support body 316 further comprises four retention bumps 324 evenly allocated in lengthwise sides of the support body 316. In addition, the supporting body 316 further comprises a curved arm 326 adapted for connecting the support body 316 with the base portion 318. The contact beam 320 with a contact tip 328 is formed with, and extends from, the base portion 318 at a bend 330 at a generally forty-five degree angle to the contact tip 328 for elastically contacting with a bonding pad of a processor. A curved foot 332 extend from the bottom of the supporting body 316 is adapted to connect the solder ball pad 322 for receiving a solder ball. Refer to FIG. 13, the contact beams 320 of the metal contacts 314 in the LGA socket 300 are warped by pads 336 of the CPU 334 to establish electrical connection therebetween as soon as the clip 306 is closed to and locked on the stiffener 302 by the lever 308. However, the contacts in existing LGA socket have only one contact portion to electrically connect with pads of the processor. As a result, there are certain risks of opening in some conducting path between the processor and the socket while the processor is mounted in the LGA Socket. At the same time, a single conducting path would result in high impedance as well against the application of high power connectors.
U.S. Pat. No. 6,694,609 issued to Lapata on Feb. 24, 2004 discloses a LGA contact terminal 400 with two contact arms 420 for solving foregoing problems. However, the contact arms 420 of any LGA contact terminal 400 have a high possibility of getting short by contact arms 420 of the other contact terminal 400 adjacent thereto while contact arms 420 of LGA contact terminals are deflected by pads of CPU. It is also noted that other approaches also use two similar deflectable contact arms respectively extending from two sides of a main body of the contact to result in two contacting points for lowering the impedance. Anyhow, similar to Lapata, because the downwardly deflected contact arm is closer to that of the adjacent contact, there is high possibility to form shorting between the adjacent two contacts while both the deflectable contact arms are downwardly pressed by the CPU. Accordingly, there is a need of providing an improved contact terminal structure adapted for keeping the contact arms with an enough space to prevent all contact terminals from unwilling short.
Hence, it is desired to have an electrical connector with dual contact portion to deal with the problems stated above.